Increased receptor activator of nuclear factor kappa B ligand expressed on B10 cells in rheumatoid arthritis / 北京大学学报(医学版)

OBJECTIVE@#To detect receptor activator of nuclear factor kappa B ligand (RANKL) expressed on B10 cells in rheumatoid arthritis (RA) and to evaluate the correlation between RANKL-producing B10 cells in RA and clinical features and laboratory parameters, trying to reveal the possible role of B10 cells in the pathogenesis of RA and the potential mechanism of impaired immunosuppressive capacities.@*METHODS@#25 RA patients and 20 healthy volunteers were enrolled. These RA patients did not received treatment with glucocorticoids, disease-modifying anti-rheumatic drug and biologics during the recent half of a year. The levels of RANKL-producing B10 cells were measured by flow cytometry (FCM) and polymerase chain reaction (PCR). The correlation between the frequencies of RANKL-producing B10 cells in RA and clinical data, laboratory parameters were analyzed. The role of tumor necrosis factor α (TNF-α) and interleukin 1β (IL-1β) in inducing RANKL expression in B10 cells was evaluated by in vitro stimulation assay. Independent samples t test, Pearson and Spearman correlation were used for statistical analysis.@*RESULTS@#B10 cells were capable of producing RANKL at a low level in health controls. The frequencies of RANKL-producing B10 cells were markedly higher in RA patients than in health controls (3.65%±1.59% vs. 2.25%±0.68%, P<0.01). The frequencies of these cells correlated positively with RA tender joint counts, swollen joint counts and disease activity score in 28 joints (DAS28) (r=0.479, P=0.035; r=0.519, P=0.008; r=0.526, P=0.019). However, no correlation was found between these cells and RA patient age, disease duration, or the levels of erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), rheumatoid factor (RF) and anti-citrullinated peptide antibody (ACPA). After in vitro stimulation by TNF-α, but not IL-1β, B10 cells isolated from healthy donors demonstrated fundamentally upregulated expression of RANKL.@*CONCLUSION@#Our studies showed the frequencies of RANKL-producing B10 cells were markedly higher in RA patients, and their frequencies were positively correlated with RA tender joint counts, swollen joint counts and DAS28. These findings suggested that B10 cells might be involved in RA bone destruction.

Regulatory B Cells Are Inversely Associated with Disease Activity in Rheumatoid Arthritis

PURPOSE: The function of regulatory B lymphocytes is known to be abnormal in inflammatory diseases. However, a recent study indicates that IL-10+ B cells seem to be expanded in rheumatoid arthritis (RA). Therefore, the state of IL-10+ B cells in the peripheral blood from RA patients and healthy controls were investigated. MATERIALS AND METHODS: CD19+ cells in peripheral blood mononuclear cells were purified from blood samples of RA patients and age and gender-matched healthy controls, and stimulated with CD40 ligand and CpG for 48 hours. Then, intracellular IL-10 in CD19+ cells was analyzed using flow cytometry. RESULTS: There was no significant difference in the proportion of IL-10+ B cells between 10 RA patients and 10 healthy controls (RA, 0.300+/-0.07 vs. healthy control 0.459+/-0.07, p=0.114). The proportion of induced IL-10+ B cells to total B cells in RA patients was significantly higher than those in controls (RA, 4.44+/-3.44% vs. healthy control 2.44+/-1.64%, p=0.033). However, the proportion of IL-10+ B cells to total B cells correlated negatively with disease activity in RA patients (r=-0.398, p=0.040). Erythrocyte sedimentation rate or C-reactive protein or medication was not associated with the proportion of IL-10+ B cells. CONCLUSION: The proportion of induced IL-10+ B cell increased in RA patients compared to healthy control, however, negatively correlated with disease activity in RA.

BAFF promotes regulatory T-cell apoptosis and blocks cytokine production by activating B cells in primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is a chronic and slowly progressive cholestatic liver disease of autoimmune etiology. A number of questions regarding its etiology are unclear. CD4+CD25+ regulatory T cells (Tregs) play a critical role in self-tolerance and, for unknown reasons, their relative number is reduced in PBC patients. B-cell-activating factor (BAFF) is a key survival factor during B-cell maturation and its concentration is increased in peripheral blood of PBC patients. It has been reported that activated B cells inhibit Treg cell proliferation and there are no BAFF receptors on Tregs. Therefore, we speculated that excessive BAFF may result in Treg reduction via B cells. To prove our hypothesis, we isolated Tregs and B cells from PBC and healthy donors. BAFF and IgM concentrations were then analyzed by ELISA and CD40, CD80, CD86, IL-10, and TGF-β expression in B cells and Tregs were measured by flow cytometry. BAFF up-regulated CD40, CD80, CD86, and IgM expression in B cells. However, BAFF had no direct effect on Treg cell apoptosis and cytokine secretion. Nonetheless, we observed that BAFF-activated B cells could induce Treg cell apoptosis and reduce IL-10 and TGF-β expression. We also showed that BAFF-activated CD4+ T cells had no effect on Treg apoptosis. Furthermore, we verified that bezafibrate, a hypolipidemic drug, can inhibit BAFF-induced Treg cell apoptosis. In conclusion, BAFF promotes Treg cell apoptosis and inhibits cytokine production by activating B cells in PBC patients. The results of this study suggest that inhibition of BAFF activation is a strategy for PBC treatment.